Abstract: Disclosed is a FPGA cell and array structure which use FN tunneling for program and erase. Each cell comprises a switch floating gate field effect transistor and a sense floating gate field effect transistor with the floating gates being common and the control gates being common. Programming of a cell is effected by voltage biasing the common control gate line and the source/drains of the sense transistor. The source/drains of the sense field effect transistor are formed from buried doped layers (e.g. N+ in a P-doped substrate) which are formed prior to formation of the polysilicon floating gate and control gate. Lateral diffusion of dopant from the buried source/drains into the channel beneath the floating gate facilitates electron tunneling during erase and program operations, and the graded junctions of the buried source/drains lower band-to-band tunneling leakage.

Abstract: In an FPGA, nonvolatile reprogrammable interconnect cells which have a switch transistor and at least one second transistor for programming and sensing, or a second transistor for sensing and a buried N+ region for programming the cell, use a high voltage on the common control gate for the cell erasing operation. The source/drains of the switch transistor are grounded. By placing an intermediate voltage on the source/drains of the second transistor, erase times can be reduced and test costs can be significantly lowered.

Abstract: Disclosed is a FPGA cell and array structure which use FN tunneling for program and erase. Each cell comprises a switch floating gate field effect transistor and a sense floating gate field effect transistor with the floating gates being common and the control gates being common. Programming of a cell is effected through a buried bitline in juxtaposition with the switch transistor and the sense transistor over which are the floating gate and the control gate. The sense transistor can be fabricated simultaneously with fabrication of the switch transistor whereby the two transistors are identical in dopant concentrations.

Abstract: The present invention provides for an improved EPROM transistor cell which forms the programming portion of the programmable interconnect interconnect of an FPGA integrated circuit, and a method of manufacturing the EPROM cell. The EPROM cell has a floating gate disposed over a P region of the substrate. Aligned with one edge of the floating gate and at the surface of the substrate is a lightly doped P- region; on the opposite edge of the floating gate is a heavily doped N+ region. A control gate lies over the P-, P substrate and over the N+ region. N+ regions are formed at the opposite edges of the control gate. One N+ region is contiguous to the P- region and forms the source of the EPROM cell and the other N+ region is connected to the N+ region under the control gate and forms the drain of the EPROM cell. This structure allows for easy process control of the V.sub.

Abstract: Disclosed is a FPGA cell and array structure which use FN tunneling for program and erase. Each cell comprises a switch floating gate field effect transistor and a sense floating gate field effect transistor with the floating gates being common and the control gates being common. Programming of a cell is effected by voltage biasing the common control gate line and the source/drains of the sense transistor.

Abstract: A programmable interconnect which closely integrates an independent switching transistor with separate NVM programming and erasing elements. The programming element is an EPROM transistor and the erasing element is a Fowler-Nordheim tunneling device. A unitary floating gate is shared by the switching transistor and the NVM programming and elements which charge and discharge the floating gate. The shared floating gate structure is the memory structure of the integrated programmable interconnect and controls the impedance of the switching transistor.